Add the possibility to use certificates managed outside of NPM

Is your feature request related to a problem? Please describe.
I am unable to use SSL certificates that are managed outside of Nginx Proxy Manager.
Right now my only solution is to reimport the certificates manually every time they are renewed, which is not convenient. Due to external constraints, I cannot manage these certificates inside of NPM.

Describe the solution you'd like
It would be great to be able to bind a local folder (in Read Only) to a predefined location inside NPM, that would be periodically scanned for available certificates. NPM would then allow to use them normally.
In addition, it would also be great that NPM automatically detect when they are renewed, and reload the related hosts before the expiration.

Thank you.

The issue names no files, tests, or entry points. Start by tracing certificate storage and import paths, proxy-host certificate usage, and host reload behavior in Nginx Proxy Manager, then inspect how Docker local-folder mounts are configured. Done means externally managed certificates can be discovered, refreshed, and used by hosts without manual reimport.